FISHES 251 



Median, caudal, locomotion, and steering (tail), 

 dorsal (back) steering, 

 anal (vent) steering. 

 Body very muscular. 

 Internal Structure. 

 Digestive system. 



Teeth for prehension, not chewing. 

 Stomach, with caeca, powerful fluids. 

 Intestine short and large, liver large. 

 Circulation. 



Heart two chambered, anterior, ventral. 

 Blood flows to gills, to body, to heart, to gills, etc. 

 Nervous system. 



Brain, separate parts for different functions (result), 

 Spinal cord, dorsal, protected by vertebrae. 

 Air Bladder. 



Outgrowth from throat. 

 Function: to regulate depth. 

 Homologue of lung. 

 Life history. 



Eggs small and numerous. (Why?) 

 Externally fertilized. 

 Slight parental care, many enemies. 

 Embryo retains yolk sac for food. 



Grows gradually, not by stages. (Why?) 

 Life history of the salmon. 

 Adaptations. 



See summary in text. 



